<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./styles/index.css" />
    <title>Document</title>
  </head>
  <body>
    <div id="app" class="score-case">
      <div class="table">
        <table>
          <thead>
            <tr>
              <th>编号</th>
              <th>科目</th>
              <th>成绩</th>
              <th>操作</th>
            </tr>
          </thead>
          <tbody v-for="(item, index) in list" :key="item.id">
            <tr>
              <td>{{item.id}}</td>
              <td>{{item.subject}}</td>
              <td class="red">{{item.score}}</td>
              <td><a href="#" @click="del(item.id)">删除</a></td>
            </tr>
          </tbody>
          <tbody>
            <tr>
              <td colspan="5">
                <span class="none" v-show="list.length === 0">暂无数据</span>
              </td>
            </tr>
          </tbody>

          <tfoot v-show="list.length >0">
            <tr>
              <td colspan="5">
                <span>总分：{{total}}</span>
                <span style="margin-left: 50px">平均分：{{avg}}</span>
              </td>
            </tr>
          </tfoot>
        </table>
      </div>
      <div class="form">
        <div class="form-item">
          <div class="label">科目：</div>
          <div class="input">
            <input v-model="subject" type="text" placeholder="请输入科目" />
          </div>
        </div>
        <div class="form-item">
          <div class="label">分数：</div>
          <div class="input">
            <input v-model="score" type="text" placeholder="请输入分数" />
          </div>
        </div>
        <div class="form-item">
          <div class="label"></div>
          <div class="input">
            <button class="submit" @click="add">添加</button>
          </div>
        </div>
      </div>
    </div>
    <script src="../vue.js"></script>

    <script>
      const app = new Vue({
        el: "#app",
        data: {
          list: [
            { id: 1, subject: "语文", score: 20 },
            { id: 7, subject: "数学", score: 99 },
            { id: 12, subject: "英语", score: 70 },
          ],
          subject: "",
          score: "",
        },
        computed: {
          total() {
            let total = 0;
            this.list.forEach((item) => {
              total += item.score;
            });
            return total;
          },
          avg() {
            return this.total / this.list.length;
          },
        },
        methods: {
          del(id) {
            this.list = this.list.filter((item) => item.id !== id);
          },
          add(){
            if(this.subject.trim() === '')return alert('请输入科目名称'); 
            if(this.score.trim() === '')return alert('请输入成绩');
            this.list.unshift({id:Date.now(),subject:this.subject,score:this.score})
            alert('添加成功')
            this.subject = ''
            this.score = ''
          }
        },
      });
    </script>
  </body>
</html>
